1. Field
This field relates to navigating in a three-dimensional environment.
2. Related Art
Systems exist for navigating through a three-dimensional environment to display three-dimensional data. The three-dimensional environment includes a virtual camera that defines what three-dimensional data to display. The virtual camera has a perspective according to its position and orientation. By changing the perspective of the virtual camera, a user can navigate through the three-dimensional environment.
A geographic information system is one type of system that uses a virtual camera to navigate through a three-dimensional environment. A geographic information system is a system for storing, retrieving, manipulating, and displaying a substantially spherical three-dimensional model of the Earth. The three-dimensional model may include satellite images texture mapped to terrain, such as mountains, valleys and canyons.
The virtual camera in the geographic information system may view the spherical three-dimensional model of the Earth from different perspectives. An aerial perspective of the model of the Earth may show satellite images, but the terrain may be difficult to see. On the other hand, a ground-level perspective of the model may show the terrain in detail.
To transition from an aerial perspective to a ground level perspective, U.S. Patent Application Publication No. 2009/0259976 by Varadhan et al. describes an example method of swooping between perspectives. Varadhan describes reducing a distance between the virtual camera and the target and determining a tilt value based on the reduced distance. Then, the virtual camera is positioned according to the tilt value and the reduced distance.
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